Prefolded for convenience. All Chemex Coffeemakers used together with the scientifically designed, patented ChemexBonded Filters, will guarantee that this pourover brewing process will deliver the perfect cup of coffee, without any sediments or bitter elements. It's Thicker (20-30% more than the competition) specialty fiber filter design keep bitter elements, oils, and grounds in their place (and out of your cup). The cone-shape ensures uniform extraction for pure coffee flavor.